pex contains the Python packaging and distribution libraries originally available through the
twitter commons but since split out into a separate project.
The most notable components of pex are the .pex (Python EXecutable) format and the
associated pex tool which provide a general purpose Python environment virtualization
solution similar in spirit to virtualenv. PEX files have been used by Twitter
to deploy Python applications to production since 2011.

To learn more about what the .pex format is and why it could be useful for
you, see What are .pex files? For the impatient, there is also a (slightly outdated) lightning
talk published by Twitter University: WTF is PEX?.
To go straight to building pex files, see Building .pex files.